1. Statement of the Technical Field
The present disclosure relates to systems and methods for reducing noise and improving the quality factor of resonators used in precision oscillators. More specifically, the present disclosure relates to systems and methods that use an eigenmode of resonator vibrations as a frequency source along with another eigenmode of the same family that is excited nonlinearly.
2. Description of the Related Art
Typically, oscillators exhibit a variety of instabilities. These include aging, noise, and frequency changes with temperature, acceleration, ionizing radiation, power supply voltage, shock, and vibration. The suitability of oscillators for a specific application is limited by deterministic phenomena, such as environmental effects. In other instances, stochastic (random) processes establish the performance limitations. Except for vibration, the short-term instabilities almost always result horn noise associated with the operation of the oscillator.
Noise can have numerous adverse effects on system performance, including: (1) limiting the ability to determine the current state and the predictability of precision oscillators, (2) limiting synchronization and syntonization accuracies; (3) limiting a receiver's useful dynamic range, channel spacing, and selectivity; (4) causing bit errors in digital communications systems; (5) causing loss of lock and limiting acquisition and reacquisition capability in phase-locked-loop systems; and (6) limiting radar performance, especially Doppler radar. It should be noted that this list of adverse effects is shown by way of example only, and additional adverse effects may be attributed to noise.
In a properly designed oscillator, the resonator is the primary noise source close to the carrier frequency, and the oscillator circuitry is the primary source far from the carrier frequency. Current resonators use an eigenmode of vibrations as their frequency source. Proprietary designs of the resonator geometry, electrode geometry and mounting supports define the quality factor of the resonators and its noise characteristics.